From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758690Ab3KIGzS (ORCPT ); Sat, 9 Nov 2013 01:55:18 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33651 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932979Ab3KIGxH (ORCPT ); Sat, 9 Nov 2013 01:53:07 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ming Lei , Aaro Koskinen , Simon Baatz , Russell King - ARM Linux , Will Deacon , Catalin Marinas , FUJITA Tomonori , Tejun Heo , "James E.J. Bottomley" , Jens Axboe , Andrew Morton , Linus Torvalds Subject: [PATCH 3.11 65/94] lib/scatterlist.c: dont flush_kernel_dcache_page on slab page Date: Fri, 8 Nov 2013 22:52:11 -0800 Message-Id: <20131109065208.874792878@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.rc0.dirty In-Reply-To: <20131109065204.252462489@linuxfoundation.org> References: <20131109065204.252462489@linuxfoundation.org> User-Agent: quilt/0.60-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ming Lei commit 3d77b50c5874b7e923be946ba793644f82336b75 upstream. Commit b1adaf65ba03 ("[SCSI] block: add sg buffer copy helper functions") introduces two sg buffer copy helpers, and calls flush_kernel_dcache_page() on pages in SG list after these pages are written to. Unfortunately, the commit may introduce a potential bug: - Before sending some SCSI commands, kmalloc() buffer may be passed to block layper, so flush_kernel_dcache_page() can see a slab page finally - According to cachetlb.txt, flush_kernel_dcache_page() is only called on "a user page", which surely can't be a slab page. - ARCH's implementation of flush_kernel_dcache_page() may use page mapping information to do optimization so page_mapping() will see the slab page, then VM_BUG_ON() is triggered. Aaro Koskinen reported the bug on ARM/kirkwood when DEBUG_VM is enabled, and this patch fixes the bug by adding test of '!PageSlab(miter->page)' before calling flush_kernel_dcache_page(). Signed-off-by: Ming Lei Reported-by: Aaro Koskinen Tested-by: Simon Baatz Cc: Russell King - ARM Linux Cc: Will Deacon Cc: Aaro Koskinen Acked-by: Catalin Marinas Cc: FUJITA Tomonori Cc: Tejun Heo Cc: "James E.J. Bottomley" Cc: Jens Axboe Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- lib/scatterlist.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -577,7 +577,8 @@ void sg_miter_stop(struct sg_mapping_ite miter->__offset += miter->consumed; miter->__remaining -= miter->consumed; - if (miter->__flags & SG_MITER_TO_SG) + if ((miter->__flags & SG_MITER_TO_SG) && + !PageSlab(miter->page)) flush_kernel_dcache_page(miter->page); if (miter->__flags & SG_MITER_ATOMIC) {